Filter



n 1952 M. B. HEFTLER FILTER 2 SHEET$-SHEET 1 Filed Sept. 19, 1947 INVENTJune 24, 1952 M. B. HEFTLER FILTER 2 SHEETSSHEET 2 Filed Sept. 19, 1947Patented June 24, 1952 OFFICE FILTER Maurice B." Heftl'er, 'GrossePointe Park, Mich. Applicationseptember 19, 1947, Serial N0. 774,920

This .invention relates to improved arrangements to limit or determinethe spacing between overlying layers orsheets'in various arrange mentsand in variousapplications and especially when they are to be closelyanduniformly spaced or. when it is desired to have a verysimplespacingmeans integral with the several layers.

This application is a continuation in partof abandoned application583,601; filed March 19, 1945, which. itself was a continuation in'partof abandoned application 4154,1'79; filed Augustfi, 1942.

This invention also relates to filtersxandmore particularlyto edge typefilters, a type that has come into extensive use, and which ischaracterized by the fact that the passages throughwhich the liquidpasses for separatingthetforeign matter therefrom are between two.adjacent and usually parallel layers or sheets of a material" (such asmetal) which thus present their edges to the direction of the flow. areoften. arranged in closely spaced and juxtaposed relationship.

In its broader aspects,. the objects of this invention are to provide anarrangement for an improved means (preferably integral) to predetermineorlimit the generally uniform spacingof layers, particularly wheresuchlayers are quite thin and uniform and where the spacing is even Iless thanthe layer thickness.

Other and more specific objects are. to provide an improvedconstructioirfor. edge filters and their spacing means which will givethe minimum deformation of the filtering layersfor agiven widthof slotand filtering area, in which the several layers may be identical andeasily. and cheaplymanufactured, and in which ahigh degree of-faccuracyand uniformity may be achieved commercially.- The objects alsoincludetheforming of such filter layers with. their spacing means with aminimum deformation of the material thereof and the predeterminingofsaid spacing by the layer thickness and by the angle of a deformedportion.

This invention also has. for its objects the making of an edge filter ofthe type in which the spacing means are integral with the material ofthe layers or elements which form the edges of the filtering slits, butwhich, as compared with the types of construction disclosed by the priorart, can. be made of relatively thin material, such as sheet metal, by asimple stamping operation so as to effect a.saving in material cost;and/or in'such amanner to obtain a filtering slit which may be as'narrowas desired and Such layers or sheets I 4 3 Claims; (Cl. 210-169)materially narrower than the layer thickness'if desired; and/or toobtain agreater 'eff'ectivefiltering area.

Principal objects of the invention, therefore,

are to provide asimpler, sturdier, and cheaper construction for filtersof the edge type, which also increases the fineness of thefilteringslits for a given layer thickness.

Other and more specific objects of the invention will'be apparent fromthe following description and claims which will be understood by reference to the accompanying drawings, wherein,

Fig. 1 is a'sectional view of a filter illustrating.

one form of application of my invention;

employed in the construction illustrated in Fig.1;

Fig; 3 is an enlarged sectional fragmentary view, taken in a planecorresponding withv the line 3-3 of Fig. 2, andshowing several elementsFig. 6 is a plan View of. a filtering element illustrating another formof the invention;

Fig. 7 is an enlarged fragmentary sectional,

view ofv a portion of a stack of elements like that illustrated in Fig.6, and taken in a indicatedby the line I-'I thereof;

Fig. 8. is. a perspective viewofa fourth form.

of the invention;

Fig. 9 is a sectional view of Fig. =Btaken. in a plane indicated by thelined-9 thereof;

Fig. 10' is a plan view of a fifth and preferred form of the invention;

Fig. 11 is a sectionalview takentina plane shown by I II I in Fig. 10;and.

Fig. 12 is a sectional view takenin a planeshown by I2,I2 in Fig. 10;and

Fig. 13 is a perspective viewtaken of a section through a stack oflayers forming a sixth embodiment of the invention.

Referring nowto Fig. 1 wherein there. is. illustrated one application ofmy invention, ahead I I is provided.with. an inlet. IZand an outlet-13,. preferably screw threaded for connection other transparentmaterial. Fluid entering the Fig. 2 is aplanview of one of the elementsplane as inlet I2 passes to the interior of the bowl l4 through llb.Mounted within the bowl I4 is a stack l5 of filtering elements which areheld in assembled and operative relation upon a noncircular stem IT by anut 18 screwed on one end of said stem, the other end of which is screwthreaded into the head II to hold the stack in concentrically spacedrelation to the bowl l4 and with the bottom of the stack some distancefrom the bottom of the bowl thereby to permit free access of the fluidto the whole outer surface of the filter stack.

The filter stack I5 is made up of a number of substantially identicaldisclike elements 19, such as those illustrated in Figs. 2 and 3,stacked one upon another, such elements in turn being supported on athick washer 2B which is imperforate except for an opening through whichthe threaded lower end of the stem I! passes. As shown in Fig. 2, eachof the elements 13 is provided with a noncircular aperture 2| to fit andreceive the stem l1 and with a plurality of arcuate perforations 22bounded by an outer annular band or rim extending entirely around theouter portion of each disclike .element. Each element has formed in itsmall frusto-conical bosses 23 preferably formed in the said outerannular band.

When the filtering elements 19 are stacked, the frusto-conical bossesare arranged in engagement as shown in Fig. 3, from an examination ofwhich it will be apparent that the adjacent flat surfaces of each pairof elements are spaced from each other so as to form restricted passages26. The spacing and arrangement of the arcuate perforations 22 andprojections 23 is such that when the discs are stacked as shown theperforations 22 are in registering alignment toprovide a plurality oflongitudinally extending passages through the stack.

Nut l8 keeps the elements in this assembled relationship against axialdisplacement. It is not essential that the stem ll be of non-circularcross section to prevent an angular displacement of the elements, as thenesting of the bosses is quite sufiicient for this purpose, however,this provision of a non-circular stem I1 cooperating with acomplementary hole 2| is a great convenience in assembling,

The manner in which the filter operates is in accordance with the usualoperation of edge filters, when the stacked discs or elements areassembled as shown in Fig. 1 and fluid to be filtered is admittedthrough inlet l2, the fluid flowing through passage I lb fills theinterior of the bowl II. The fiuid will then flow through the restricted passages 26 between the elements to the longitudinal passagesformed by the arcuate perforations 22 and thence to chamber 2-4 whichcommunicates with the outlet I3. As will be apparent the stack ofelements forms an eificient filtering medium that not only prevents thepassage of any particle of greater thickness than the width of therestricted passages 28 but also restricts the passage of much smallerparticles which tend to cling to the surfaces and edges of the discs.

From Fig. 3, it is apparent that contact between the elements will beefiected only on the conical surfaces of the bosses 23 and that, aspreviously stated, the remainder of the elements will be separated toform restricted fluid passages, the width of each passage (the distancebetween the two adjacent elements l3) being proportional to thethickness of the stock or sheet material from which the discs arefabricated and depend- .portion 31 of the disc.

me also on the angle which the sides of the frusto-conical projectionsform with the flat faces of the discs. Such an angle is indicated at Ain the embodiment illustrated in Fig. 5. It will therefore be apparentthat the width of the filtering slit 26 is independent of the height ofthe projection or boss 23 above the plane of the main surface of theelement.

Figs. 4 and 5 illustrate another form of element to carry out theinvention. In this form, the de flected portions or projections, insteadof being of frusto-conical form, are formed by inclined surfaces made bybending down a'plurality of small tabs 28 on the sides of the arms 29that connect the outer rim 30 with the hub or central Fig. 5 illustratesthat when the discs of this type are stacked with the deflected tabs ofone disc nested within the deflected tabs of the next adjacent disc, thediscs are spaced from each other in a manner identical with the oneshown in Fig. 3 and so as to form restricted fi-uid. passages betweenthe adjacent surfaces of each pair of discs.

In Figs. 6 and 7 another form of filtering element embodying myinvention is illustrated. In this form, the rim portion 34 of eachelement 32 is deflected to form the frustum of a cone with its largebase up and the nesting portion 33 is also in the form of a frustum of acone but opening in the other direction and the small base of whichforms a flat hub having a non-circular opening 35 to receive a stem suchas H. Spaced arcuate shaped openings 31 are provided in the rim portion34 so that, when such elements are stacked, they will be so guided bythe non-circular hole 35 and stem I! that apertures 31 will be inregister to form longitudinal channels.

With the slopes of the two frusta 33 and 34 as shown, it will beapparent from Fig. I, that, when the elements are stacked, the frusta 33will nest while the rim portions 34 are kept separated to form narrowrestricted fluid passages therebetween, through which the fluid to befiltered may pass to the channels made by registering apertures 31 andthence to the outlet of the filter.

In Figs. 8 and 9 another form of filtering stack is illustrated whichwould be useful in an assembly of a type different from that illustratedin Fig. 1. In this embodiment, the elements take the form of longrectangular pieces 40, preferably of sheet metal, each element beingprovided with frusto-conical projections 4|. Any number of such elementsmay be assembled so that the projections 4| nest within one another asshown in Fig. 9, any suitable means being used to maintain them inassembled relationship.

Only a few elements are shown in Fig. 8, but it will be understood thata much larger number of elements can readily be assembled in this mannerso as to form a foraminous partition which may be used to separate twocavities, not shown, yet to permit the passage of clean fluid from oneside of the partition to the other while preventing the passage offoreign matter larger than the lam nar passages existing betweenadjacent elements.

Generically speaking, a preferred edge filter embodying my inventioncomprises a stack of substantially identical layers of one piece or asseparate elements having portions of their surfaces deformed ordeflected, said deflected portions of one element being in nestedcooperative relation and preferably in contact with the deflectedportions of adjacent elements and coopatomic emtingwtnerewithtopredeterminethe minimum pace between:theielementsvsoas to define-afiltering .slit; therebetween, for. the. passage of lfluid.

tolthelexclusion of foreignlmatter.

In edge filteringstacks made accordinggto myrangements in. which theindividual elementsare.

not only piled vor. stacked. in nested engagement upon one another, butare-also. orientated simie larly, .01 .to cuse-amoraprecise language.borrowedefrom geometry, the position. in spacer of antaelement lis iderived. from; \the position. ofv the firsttelementw-of the stack.-by,--a simp1e.transla tion, without rotation, the..direction of, suchtranslation beingindicatedby line T.T,-. in Eigs.

5 and l.7I-- The contact engagement. of.- i the: dew;

flected and. IIBSti'IIgpPOI tiOIlSOf the elementswith eachothendetermines theaamount of this til -3,115?- lation, on: in other,words, the distances between: homologous .points. of adjacent elements.If, D be. thenanglethat. such deflected portion: makes with-ltheoaforesaide direct-ionaT-Jl, .then this; translation isiequal to tcosec. D, whereztzis the.-

thickness of the material. 1

In the form of Fig. 5, where the surface-adjacent to. and. bounded: bythe edge of. the :element is.at 'right-angles=.-(E -to-.the aforesaiddirection, the..width v ofthe slitis the. dilference. betweenthe-..amount:0f. the translation and the, thick-- nessoiethe stock andwill-.begiven loy the for-- As a practical example,

mulazl t. (cosec.. D-l) assumingtheistock to be.-.005" thick and theangle to@be.45 degrees, the widthof theslit would.

In. the. above, example, the distance between homologous points ofadjacent elements-is equal tothethicknessof the stockout-ofgwhich theelement is .1made,. which. thickness is notchanged in, the deflectedportion, divided .by the .sineof, This. distance is equal to 005'! timesthe, cosecanttof 45, which. is 1.414214, audit is Incasured along lineT"T.oi Figure 5. 'I .-'I' is par..-

allel to the axis ofithe stack of elementsand each element isperpendi'cularto the axis-so thespaceleftbetween elements is theabovetranslation lathe-form of Figs. 6 and v, asthe'angle E'ls greater thanangle-D the edge portions willb'e kept'at' a -distance and in this case,the width of" th"S1itWl11 be giverrby the :more general formula? t(CosecsD-cosec. E). Assuming again that'thestock"is".005 thick andthe'angleD is45"-degrees; if angle E is assumed to be degrees, the widthofjthe vslit willhbe' .0013!!! Comparin theemhodinent'of Figures 1,tos3' with the form ofnFigures 8'and 9; it is.noted that.

the conically= deformed portions 23 of. thefirst form do nothave holesor central openings and hence areto be preferred iwhere more. strengthorresistance to bendingisdesiredwhile the coni.

calpositionsdlvvith their central openingsnare easier to manufacture.Thus. .either arrangement may beemployed as may be desirableljj In:Figures 8 and 9' the openings throughthe."

truncated conical portions M. may serve to. re:- ceive securing screwsor colts. not. shown but lik'e'the one shown in thee-enter of Fig.18,,which bolt, serving toholdthe several layers withtheir portionszl inengagement, is through the enreceiving. recesses 54:1.

tral. holes of an homologous ;set of deformed. D913.- tion sylike-A I lThe embodiment of i this inventionnwhichfl is; preferred: 1 at --the-.present time is; shown ures 10,11; and-12 in which thedisk-likeelementtogether;

. Each element has annular inner andoutenrim portionsjz and 58respectively which lie-.in-panallel planesand are; connectedbyi-angangularlyr extending portionwfia which is. as shown-,concentricwith 60: and 58. Uniformlyishapedopenxings" 64 are spaced atequalanglesvto interrupt the angular portion 62Iandalso extends, radially:

intvard'into: portion :52 and radially: outward into 1' port-ion 58:The: angular. portion 62 :is. preferably formedla-s a surface ofrevolutionand-specifically: as -a=xsurface of" a truncated icone; ofiIwhich: the:

generating angle: corresponds to the angleDzjof.

Fig. ,5. Portions .62 shave-appreciable. .areas-sheld together topredetermine the minimummspacing; which is: the samev forparallelportions '52 and .58

tVliile-surface; or: portion 62, is preferably a" surface-of; atconeyet-inrview= of its interruptions:-

by openings 64, the material: between theizpopeni-qings may alsmbeaformed: as -plane rbends andth'us not; vas surfaces ofxrevolutiom Infact the'ac tual elements; thewdifierence isrnotr'readi-ly ape parentupon inspection;

It will be seen that the rim or filtering edger 50+ isentirely-unobstructedcor uninterrupted and yet" spacing and supporting"portions 62'. are-s:

ca-ted as closetoythissouter --rim as.- practical. to

thusgive a. large filteringarea andtshort lengths of unsupportedmaterial in the layers;

The openings 154;; identically! oriented in successive. elements;collectively form: channels: whichc, serve; to conductzfiltrate; frombetween parallel portions .58 to between parallel; portions--present;th'e slope 52,. If theseqopenings WereanOt ing; portionsSZuofxadjacent elements, in contact with each oth'erroverr-appreciableareas, would effectively block" out. all outlet "from. the stack offiltering elements.

The. openingsrfi lxreduce the restriction of "the? filter byreducing-the length" ofthe-s1it path's into the--main-central opening60.? Also tlieinner edges '1 of :these; openings would also filter"orcatch any material, which passedrith'e outer! rim if thatWGI'GIJOSSiblG-U The openings 41 of th'e several elements whichcollectively form channelsalso serve to increase the flowcapacity-,ofthe stack'of filtering elements above what would he'obtained: from then mainzcentral opening 60 alone:

The large .-area, central openingnfin alsorlhelps":

reduce the-restriction of the .insidegretumtpatln In... the several..species ;above,: each; of; thersew erallayers is a separate piece orel-ements, However, this is. not" essential to thessuccessfulzprace ticeor} the. present invention sincexall or: a pluralitya oithe'; several;layers .zot; an :e'dgewfiiterw ac cording to this invention may be ofone piece or strip of sheet material (preferably thin and of uniformthickness) which may be folded or the like but preferably is wound aboutan axis as shown in the embodiment of Fig. 13 (wherein the slightcurvature is not apparent).

Here the coil is in the form of a flat spiral whose axis is parallel tothe plane of the outer edges or undeformed edge portions of the coiledstrip. The several tightly coiled layers 10 each have outer edge or rimportions 12 either one of which may be the initial filtering edge or thearrangement may be such that the flow is in from each edge or rim to theuniformly spaced openings 11 which are offset to either side of thecenter of the strip to interrupt the inclined por tions 13 (which are incontact to predetermine the minimum spacing). These openings extend intothe two edge portions 12 and the central portions 15, all three of whichare parallel.

The spacing portions 13 inclined to the plane of portions at an anglesuch as D of Fig. 5 are held together by the coiling of the strip and byany suitable releasable retaining means, not shown. When wound in aspiral, the several openings Ti will not fall into exact radialalignment but will progressively be offset but the liltered fluid canfiow from an edge into the adjacent openings, through the slots betweenportions 15 into the openings of the other side and out through theother edge slots or else similarly both edges in to the two sets ofopenings.

The planes of the two inclined portions 13 form a dihedral angle or whatmay be termed a truncated dihedral angle which is uniform.

throughout and also gives a seating or self centering action. Note theradially directed dihedral angular portions in Fig. 4.

The key receiving portions 54 are used to angularly align the disks inthe same way in which they were stamped to thus distribute theunavoidable small errors which do not fall in the same way.

The large central openin permits a large and thus amply stiff centralrod or bolt and also permits the .use of a larger and stiffer rod-likemember for assembly during manufacture which is an advantage.

During stamping of this form the outer rim is not changed in thicknessbut the necessary draw in the cupping produces a very slight reductionin thickness in the inner rim which is not ordinarily used as theinitial filtering edge.

In all of the embodiments shown the several layers may be made of anysuitable sheet material 'having sufficient strength including metal, wetstrength paper particularly if sized with plastic, etc. Also in eachform illustrated to permit easy cleaning the several layers arereleasibly held or clamped together at their minimum spacing as by boltand nutl'l and I8 of Fig. l, but this also is not essential to thebroader aspects of this invention wherein the several 7 layers may becemented or otherwise permanently secured together.

It will also be noted that in each form as shown the contacting angularportions are of uniform slope or angle to give substantial orappreciable inclined areas to be in alignment and contact to thus formin effect straight supporting columns of sufficient cross sectional areafor proper strength of the filter unit. These columns need not bestraight and in addition the areas in contact may be reduced so that thecontacting angular portions are lines or points or little more thanlines or points. This will space the layers and may be preferred in somecases although the stack can not be as tightly compressed withoutdeflection of the spacing deformations. Such a form would be had if theconical portions 23 of Fig. 2 or II of Fig. 8 were surfaces ofrevolution or dimples with nonstraight side walls giving a circular orring-like contact line or nearly a line.

In all forms, the filtering may be in the several ways well known in theart, such as flow from the inside, or flow from the outside, or flow twoways from the inside and the outside to openings such as 64 of Fig. 10.

Although only certain specific embodiments of the invention have beendescribed in detail, it will be appreciated by those skilled in this orin related arts that various modifications in the form, number, andarrangement of the parts may be made and the present spacing meansemployed to advantage in various other arrangements, all within theteachings and spirit of the present invention as defined in theaccompanying claims.

I claim:

1. A filter of the edge filtering type comprising a plurality ofsubstantially identical elements arranged in a stack, each elementhaving a flat ring-shaped outer portion, a flat ring shaped innerportion co-axial with said outer portion, and lying in a plane parallelto but offset from the plane of said outer portion, and a plurality ofintermediate portions connecting said inner and outer portions and lyingon the surface of a cone co-axial with said inner and outer portions,all of said portions having substantially the same thickness and saidintermediate portions being in contact with similar portions of adjacentelements so that said inner and outer portions are held spaced slightlyaway from the inner and outer portions of said adjacent elements to formthin passages between said inner portions and between said outerportions, and said intermediate portions of said element being spacedapart circumferentially to leave passages connecting said thin passages.

2. A filter of the edge filtering type compris ing a plurality ofsubstantially identical elements arranged in a stack, each elementhaving two fiat main portions of substantially uniform thickness lyingin parallel planes spaced from each other, and a plurality of spacedconnecting portions extending from one main portion to the other at anoblique angle to said parallel planes, said connecting portions being incontact with similar portions of adjacent elements and the thickness ofsaid connecting portions being greater than the product of the thicknessof said main portions multiplied by the cosine of said oblique angle sothat said main portions are spaced slightly from the main portions ofsaid adjacent elements to form thin passages between said main portionsof said elements.

3. A metal-edge filter comprising a stack of identical thin metal plateshaving holes lined up to form passages through the plates to the end ofthe stack, the plates being spaced apart over a large part of their areato provide thin slits leading from the side of the stack to the passagesformed by the holes, each of the identical plates having a fiat mainportion and a plurality of spacing portions, each spacing portionextending from the flat main portion at an oblique angle to the plane ofthe fiat main portion towards the edge of a hole in the plate; the edge9 of the hole being out of the plane of the flat main portion of theplate.

4. In a filter of the edge filtering type, superimposed layers of sheetmaterial of uniform thickness, portions of which are spaced apartREFERENCES CITED The following references are of record in the file ofthis patent:

10 UNITED STATES PATENTS Number 15 Number Name Date Sperry Apr. 26, 1887Gobbi July 14, 1908 Adams July 1, 1913 Krause Sept. 22, 1914 Rhoads Oct.30, 1923 Benckenstein Jan. 26, 1926 Stuart Feb. 19, 1935 Mesurac Jan. 5,1937 Young Nov. 22, 1938 Braddock July 4, 1944 FOREIGN PATENTS CountryDate Great Britain Sept. 8, 1930 Great Britain July 25, 1940 GermanyJuly 6, 1940

